Heat Training: 4 Ways to Prep for Running in Hot Weather

Want to get ready for running in hot weather? 
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Check out these runner-tested heat training strategies to prep for summer races and adventures.

Despite the many world records being set in athletics, humans aren’t all that impressive compared to other species. 

• We’re slow relative to other animals.
• Our VO2 max pales in comparison to that of a hummingbird’s, and...
• We aren’t terribly strong or powerful. 

🥵But we can endure–and more specifically, we sweat as we endure. 

• Human physiology is optimized for managing heat and moving for long periods of time. 
• Our ancestors had to walk (and run) long distances in semi-arid environments to find food sources. 
• Our sweat glands, somewhat hairless bodies, and the ability to breathe through our nose and mouth are remnants of this evolutionary pressure. 

🏃‍♀️Can you learn to run in hot weather?
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As modern day runners, we usually focus on the endurance aspect of our physiology without much thought to our ability to dissipate heat.
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However, if you find yourself...

• In a cool climate...
• Contemplating a forthcoming summer race or event...
• With scorching conditions...

It might be time to explore the art and science of heat training—a pathway to unlocking your body's potential and fortifying your mind against the heat's relentless embrace. 

More and more athletes are using heat training protocols this time of year in preparation for the US Olympic Team Marathon Trials in the hot and humid conditions of Orlando, Florida on February 3rd.
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🔥For the trail runners reading this, maybe you recall Jim Walmsley’s iconic last long run/heat training session for Western States 100 back in 2021?
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Simply put, heat training places a specific stress on the body that it will adapt to over time.
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With the proper heat stimulus, your body is able to:

• ✅Improve your sweat response, which means sweating sooner and sweating more. Interestingly, the composition of your sweat changes too  (Allan and Wilson, 1971) 
• ✅Increase blood plasma volume, which can improve maximal oxygen uptake (Davies, 1979) 
• ✅Increase cardiac output, which means a lower heart rate during exercise
• ✅Decrease core temperature during exercise

Outside of the physiology itself, there are also perceptual benefits runners will gain from heat training.
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According to (Périard et al., 2016), your “thermal comfort”—how you interpret your thermal state—in hot environments improves over time with heat training. 

Ultimately, a heat training protocol can lead to better performance!
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Instead of being overwhelmed by heat stress on race day, your body will be accustomed to it, and in turn, better able to handle the additional stresses of running hard and fueling properly.
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From effective DIY methods to sauna use, in this article, you’ll learn:

• The ins and outs of heat training
• Who it's likely to benefit most, and...
• Most importantly, how to properly implement it to get the most juice for the proverbial squeeze! 

In long distance running, heat is undoubtedly a performance limiter–particularly if you’re not prepared for it.

• 🥵In ultrarunning, Western States 100 and Badwater 135 are perhaps two of the most iconic (and hot) races that athletes prepare for with heat training. 
• 🥵In Mallory Richard’s article on iRunFar.com, she discusses how hot years (95+ degrees Fahrenheit) at Western States 100 are slow years, but not necessarily DNF sentences. 
• 🥵Badwater 135 even has a whole page on their website designated to preparing runners via heat training in the sauna. 

Sub-ultra events also come with their own sets of heat-related challenges. .
Take the big city marathons, for example. 

• The higher intensity of such events paired with their often urban surroundings that increase reflected radiation are just two heat-related considerations. 
• Large crowds on the start line or during the race also add to the heat stress runners might experience at a marathon or similar road race. 
• Check out this article for an in depth discussion of heat stress factors in marathons and ultramarathons. 

Even if you have no intention of running a hot ultramarathon or a big city marathon, you’ve probably felt the strain of warmer weather the most when you emerge from a dark and cold winter season....
You know...

• 🥵That familiar stomach-churning heat you experience during a workout in early spring. 
• 🥵When what would’ve been an attainable, perhaps even comfortable, pace during those cooler winter days feels like a dead sprint. 
• 🥵As the temperature increases, so does your core temperature, heart rate, sweat rate, and perceived exertion. 

So, let’s get prepared!
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Heat training can make you a more fit and efficient runner in almost all conditions; there’s even some preliminary evidence that hints at heat training promoting similar effects to altitude training (read more here). 

As with any training intervention, there are a few caveats worth mentioning.
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👩‍⚕️1. Ask your doctor.

• Heat training is an additional stress that you’re asking your body to adapt to. 
• That being said, make sure you’ve cleared your heat training protocol with your healthcare provider beforehand. Individuals with underlying conditions might be putting themselves at risk with the addition of a heat training. 

⌚2. Time is precious.

• Heat training interventions are a matter of marginal gains. 
• If you’re an athlete who already struggles with being able to meet training requirements (enough mileage/hours), additional time spent on heat training (and traveling to your heat training facility) will most likely detract from your training rather than add to it. Fitness always comes first.

✅3. Good stress is still stress.

• Heat training in any form will add to your body’s total stress. 
• It’s important to monitor your recovery, hydration, sleep, and intensity distribution with this new stimulus. 

🚫4. More is not always better. 

• While it might be tempting to do as much heat training as possible, more volume won’t necessarily yield better results. 
• Sometimes it’s best to opt for the minimum effective dose of heat training because you’ll still get the adaptations without all of the stress.

💧5. Proper hydration is key. 

• With the additional sweating that is bound to happen in heat training, it’s imperative to maintain your hydration. 
• Take the opportunity to get a rough estimate of your sweat rate so you can better plan your fluid intake. 
• Gatorade Sports Science Institute has an online calculator that can help! While the calculator may overestimate your sweat rate since it doesn’t account for metabolic processes, it’s a helpful starting point. 

There are a few ways of approaching heat training to reap the benefits:

• Dry saunas
• Hot baths
• Steam rooms, and...
• Overdressing 

These are the four most common heat-training strategies.
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👉But the best heat training method is one that you can stick to! 
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As a general rule, if it takes you more time to travel to the place you will heat train than it will to complete the session, it might be time to consider a different method.
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Let's take closer look at each of these heat-training strategies...

1. Dry Sauna

• Probably the most popular method for heat training, the dry sauna offers an option for passive and post-exercise heat training. 
• Post exercise: when your core temperature is already elevated, hopping into the sauna for 10-20 minutes is enough.
• Passive: when done separately from exercise, the sauna requires more of a time commitment–approximately 20-30 minutes. 

2. Hot Baths AKA Hot Water Immersion

• Hot water immersion is the next best method to a dry sauna.
• Post-exercise: most effective when implemented in 20-40 minute bouts when your core temperature is already elevated. 
• Passive: when done in isolation from exercise, hot water immersion sessions should be 30-60 minutes in duration

3. Steam Room/ Wet Sauna

• If a sauna or hot bath isn’t an option, a steam room could be beneficial for simulating the effects of humidity.

4. Overdressing

• Overdressing for the running conditions can be a simple, accessible, and low-cost way to train your body to handle the heat. This method is most effective when done in 60-90 minute bouts. 

👇However, there are a couple of important caveats about overdressing:👇

• Overdressing in a temperate environment may not elicit the same magnitude of physiological adaptation one would attain by exercising in a hot environment (Ely et al. 2018)
• Wearing too many bulky layers may alter your running mechanics (just ask David Eliuk, who set a world record running a half marathon wearing 120 T-shirts.
• Overdressing can be rather unpleasant, so be ready to get gritty! 

The goal of any heat intervention is to elevate your core body temperature for an extended period of time in order to attain the desired adaptations that will prepare you to run in warmer temps, and augment your cardiovascular fitness. 

• For hot water immersion, around 104 degrees Fahrenheit 
• For the sauna, a temperature range between 180 and 200 degrees Fahrenheit is ideal. Most saunas at public gyms are set around 160-180 degrees Fahrenheit. 

At the bare minimum, Ultrarunning Coach, Jason Koop suggests that runners do 15 minutes in the sauna at 140 degrees Fahrenheit. Any less time at a cooler temperature and it’s not worth the effort. 

Heat training protocols for runners generally fall into two categories: a single or two-phase.
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The Single-Phase

• The single phase implements heat training only in the final weeks of a training block, including the taper. 
• Since the physiological benefits of heat training are quick to accrue and somewhat quick to dissipate (according to Jason Koop, in his heat training podcast episode with CTS Coach, Andy Jones Wilkins, approximately 2%-3% per day), doing a final push of heat training during a taper makes sense, but it also doesn’t leave much room for error. 

The Two-Phase Protocol

• A two-phase protocol consists of a concentrated block of daily exposure followed by a maintenance period, which includes the final tune up during the taper. 
• The two-phase protocol demands more time overall, but also provides more leeway if you miss a session or if the temperature/duration isn’t ideal. For most athletes, a two-phase protocol is the practical choice. 

Week 1 of heat training (around 5 weeks prior to target event): Adaptation

• 7 post-exercise sessions of 20 minutes in a dry sauna at 160-190 degrees F. 
• To minimize the overall stress load This concentrated heat training block could be strategically placed within a deload week in your training block.

Weeks 2-4 of heat training: Maintenance

• 20-30 minutes in the dry sauna every other day or 3x per week to maintain heat adaptations gained in the first week of concentrated heat training

Week 5 of heat training (race week): Maintenance and Taper

• 1 or 2 sessions of 20-30 minutes in the dry sauna to maintain adaptations without compromising the taper. 
• Keep at least 2 days between the final sauna session and the key event  

As a runner, heat training is a helpful tool to have in your back pocket, especially as you start to plan your race calendar! 
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There are SO many different protocols out there, but here are the main points to remember:

• Choose a method that is convenient and feasible for your circumstances
• Heat training stress is still stress–keep tabs on your recovery and total training load
• Dry sauna is the preferred heat training modality, but hot water immersion is a close second
• Post-exercise heat training sessions are shorter in duration than passive heat training sessions in isolation
• Heat adaptations are quick to accrue (6-10 days) and dissipate by ~2-3% each day 
• Give yourself enough time between your last heat training session and your big event 

 If you’re about to tackle some hot-weather running and want more info on handling less-than-ideal conditions, check out Evan’s article with 10 helpful tips for running in the heat.

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